In the summer of 1992, CIA counterintelligence analyst Sandra “Sandy” Grimes burst into the office of her boss, Paul Redmond, and exclaimed, “It doesn’t take a rocket scientist to tell what is going on here … Rick [Ames] is a Russian spy!”

Thus came the major break in a mystery that had bedeviled the CIA for years: Why were so many of its agents in the USSR being compromised to the KGB and executed? The arrests cut out the heart of the agency’s spy efforts in the USSR.

Mrs. Grimes was part of a counterintelligence team working on the problem. Aldrich “Rick” Ames, an agency officer since 1967, chiefly on Soviet matters, was one of several individuals under suspicion, chiefly because of the “extremely large sums of money” he was spending, both on a new home, a sports car and high-living with a spendthrift wife. (Ames spoke vaguely of his wife’s “inheritance,” a claim that could not be verified because wills were not open to outsiders in her native Colombia.)

Although he held some important assignments in the Clandestine Service branches dealing with the USSR, Ames was considered a so-so officer. He was unkempt in his personal appearance, he drank a bit more than was considered the norm, and his performance in various postings was uneven. Superiors chided him often about tardiness with his reports; if a particular assignment did not interest him, he tended to give it short shrift.

In her investigation, Mrs. Grimes laid out a chronology of the betrayals and Ames‘ activities, while a colleague, Dan Payne, pored over Ames‘ bank records and other financial data. Once she correlated the financial data with her chronology, she had what she would later call “an epiphany.”

CIA tradecraft encouraged officers who worked on Soviet affairs — such as Ames — to make “sanctioned contacts” with people at the Soviet Embassy, with the hope they might cultivate them to the point where they would reveal important information. Such contacts supposedly were reported in advance to the FBI to explain why a CIA officer was making such contacts.

Ames had dutifully reported some — but by no means all — of the lunches and other meetings he had with Sergey Dmitriyevich Chuvakhin, ostensibly an arms-control specialist. Sandy Grimes immediately spotted the correlations that sent her racing into Redmond’s office:

Mr. Payne’s financial analysis eventually would document that from 1985 to 1991, Ames had income of $1,326,310 from unidentified sources. The case was by no means over, and just how the CIA and the FBI worked together to put Ames behind bars for life makes for the most gripping insider account of a counterintelligence operation that you are ever apt to read. Mrs. Grimes, a 26-year CIA veteran, co-authored the book with her friend Jeanne Vertefeuille, who joined the CIA as a GS-4 typist in 1954 and worked her way through the Clandestine Service to become a station chief. She “retired” in 1992, but continued as a contract officer until her death on Dec. 29 ended a 58-year career.

Aside from his sloppy tradecraft in handling money, Ames had another fault — a low regard for women. He had known Mrs. Grimes for years — they carpooled together at one point — but during interviews with her and Ms. Vertefeuille, he made plain that “he thought he was smarter than we were” and that he “viewed us as two dumb broads.” He was wrong, and fatally so.

The KGB, of course, was fully aware of the CIA’s intense “mole hunt,” most likely on the basis of Ames‘ reports. So the Soviets floated several explanations for the breaches that seemed plausible on their face — that CIA communications were flawed, or that “an officer with a Russian name” was the source. These ploys were ultimately recognized as attempts at disinformation.

Much of “Circle of Treason” is devoted to the recruited agents betrayed by Ames, and the important information they gave to the CIA during the years when the Cold War was still serious. That most of these individuals were summarily executed emphasizes the odious nature of Ames‘ conduct.

The authors state candidly that they are not telling a complete story: “When it comes to information we believe the opposition does not know or that could prove harmful to certain individuals, we have suppressed it in our book even though it would add useful background to our story.”

The book also marks an attempt by the CIA to point up its major role in the detection of Ames — something for which the publicity-conscious FBI was quite happy to present as its own success after his arrest. Several earlier books on the Ames case were heavily FBI-centric, particularly David Wise’s 1995 work “Nightmover.”

All in all, “Circle of Treason” is a disturbing read, but an essential one for anyone interested in the intricate detail work involved in a counterintelligence investigation — and a tribute to two women who helped push it to a conclusion.